Gas, tires, oil.

So, let’s finish up this paint job (part 1, part 2). I thinned the paint for spraying, I think a lot of people have problems using spray guns because the paint is too thick. Most automotive paint has specific thinning instructions and there are tools for measuring viscosity, but here is a good rule of thumb: thin until when you pull the paint stick out of the paint, the paint running off the stick breaks into two streams (instead of one).

I thin in a separate container (necessary if it’s catalyzed paint), you can buy disposable plastic containers just for this. This way you strain thinned paint into the gun.

Double up the strainers to make sure you keep dirt out.

Here’s the paint on the trailer.

After scuffing up the surface, I taped off the stripe. This was made easier by this masker that I found at a yard sale for $2.

You put in a roll of tape and a roll of masking paper, as you pull the paper out, it puts on the tape with half over the edge of the paper.

Masking is a whole art in itself, but here are a few hints. First, it is better to under-mask rather than over-mask. This seems backwards, but think about it like this: consider the trim around the windshield, if your tape doesn’t quite go the edge you will get a little paint on the edge of the trim. But this is hard to notice (you have moved the junction of chrome and paint just slightly) and you can remove the paint later with a razor. But if the tape goes over the trim on to the painted surface you will leave a little band of the old color (or primer). And this really looks bad and is hard to fix. Same goes for a stripe like the one I’m doing here. Better to let the paint extend a little farther than leave a strip of the old color on the edge. For really high end paint jobs, they unmask the car and remask it after priming it and before the final paint just for this reason.
I don’t have a pic to show the actual taping (it takes two hands so I could hold the camera), but let me try to explain it. You hold the roll of tape in your right hand and press it down/guide it with your left hand. Keep the tape unrolled a foot or more and hold the roll close to the surface. You steer the tape with roll, the farther away the roll is, the more acurately you can tape (it takes a large movement of the roll to change the angle of the tape). Masking tape is slightly crinkly and can be steered around some very tight curves in this way. First go around the edge with tape, then follow up with the paper. When going around corners with the paper, fold it over (like a christmas present), then tape all along the fold. You don’t want it to flap when hit with air from the paint gun, it might dump trapped dust on the wet paint. When masking really big areas (like the top half of a car) I use old sheets. You can pick them up at yard sales for cheap and they work great for areas that won’t be directly sprayed. Next time we’ll mix the paint and spray it on.

I decided to repaint the green stripe on our camper and I think it will serve as a nice example of how to do a “scuff and shoot” paint job. Now, many people have their own way (and order) of paint preparation and I will certainly not represent mine as the correct way. But I will try to provide the reason for each step, so you can make your own decision. First I wiped off the spider webs and dirt with an old towel. Some people like to wash with soap and water, which is fine for a long term project, but I was going to be painting later that same day. Then I wiped it down with a paper towel (Bounty) soaked in enamel reducer.

This removes wax, oil, grease, tar and other road dirt that would clog up the sand paper and later cause “fish eyes” in the paint. Now, if you were planning on stripping something down to bare metal, you don’t need this step. On a nice paint job, the vehicle would be wiped down again, right before painting to remove grease from fingerprints that happened during sanding and taping. But, in general, don’t touch the surface with your hands (at least not casually). I wasn’t doing any body work or sanding, but I did need to scuff up the surface so the paint would stick. I used a maroon scotch-brite pad.

The large areas just need a general scuffing, it’s the edges that need special attention. This is where paint will peel and lift, so you need to get right to the edge.
Next I used a blow nozzle on my air hose to blow the dust off and blow out any dirt trapped in the seams. This is extremly important. When you use a paint gun you are blowing on the vehicle with high pressure air. Sand and dirt (and possibly leaves and dead bugs and water…) can blow out from its hiding place and then stick to the fresh paint. You have to make sure nothing is going to break loose during the painting, so, before painting you blow on all the seams and cracks with a much more intense blast of air. Everything needs to be done, the inside of bumpers, inside of wheel wells, door jambs. Chrome and emblems that are going to be taped off instead removed need to be done. I put the blow nozzle right up to the edge and go all the way around it. And when you do this, you need to be using filtered air, so your not spraying oil (from the compressor) and water (condensed out of the air if it’s humid) on the the surface.
Next time: taping (masking) and painting.